Glass pressing apparatus



June 28, 1966 J. J. TOROK GLASS PRESSING APPARATUS 2 Sheets-Sheet 1Filed Nov. 21, 1962 INVENTOR. Juuus J. TOROK BY Ejlfivi 7%a ATTORNEYSJune 28, 1966 J. J. TOROK 3,

GLASS PRESSING APPARATUS Filed Nov. 21, 1962 2 Sheets-Sheet 2 IN TOR.Juuus J. OROK BY EMA/ aw ATTORNE Y5 United States Patent 3,258,324 GLASSPRESSING APPARATUS Julius J. Torok, Toledo, Ohio, assignor toOwens-Illinois Glass Company, a corporation of Ohio Filed Nov. 21, 1962,Ser. No. 239,120 8 Claims. (Cl. 65362) This invention relates toapparatus for pressing glass and particularly to plunger and molddesign.

In the pressing of glass articles, a major consideration is the controlof heat distribution in order that the surfaces which form the glassarticle are neither too hot nor too cold. If the surfaces are too hot,sticking of the glass may occur and if the surfaces are too cold,crizzling of the glass surfaces may occur.

One of the methods heretofore used for controlling the. heatdistribution is by liquid cooling the plunger and mold as by the use ofwater. Liquid cooling is limited in its effectiveness so that thecontrol of heat distribution has heretofore been obtained by varying thethickness of the metal of the mold or plunger. Although such a design ofmolds and plungers with varying thicknesses has produced somesatisfactory results, in some instances, where the shape of the articleis complex, it has been found thatthe variation of the thickness tocompensate for heat flow in one area interferes with the heat flow inanother. Thus, in the pressing of the face plates of a television tube,which have abase and peripheral flange extending at an angle from thebase, considerable difficulties are encountered at the area of junctureof the base and flange of the plunger. 4

' It is an object of this invention to provide an improved apparatuswherein the heat flow distribution of the pressing member can be moreaccurately controlled.

It is a further object of the invention to provide such an apparatuswherein the heat flow distribution can be varied Without a completedestruction of the pressing member.

It is a further object of the invention to provide a pressing apparatuswherein the forming surface can be made of a thin flexible materialwhich can be readily replaced at relatively low cost.

Basically, the invention comprises making the pressing plunger or moldwith a hollow space which is to be filled with a fill metal cast in situto form a core. A thermal modifying member, either more or less highlyconductive than the pressing member itself, is inserted in the space anda fill metal cast in situ in the space. The thermal modifying membermodifies the heat flow distribution at the desired areas while the fillmetal cast in situ fills the remaining space and not only gives strengthto the pressing member but, in addition, provides the desired thermaldistribution through the pressing member. The thermal conductivity canbe increased or decreased by proper selection of good or bad thermalmodifying members. In addition, the overall heat dis tribution can bemodified by melting and removing the cast fill metal and replacing itwith a different fill metal having a different thermal conductivity.

In the drawings:

FIG. 1 is a vertical sectional view through a pressing apparatusembodying the invention.

FIG. 2 is a fragmentary sectional view taken along the line 2-2 in FIG.1.

FIG. 3 is a vertical sectional view through a modified form ofapparatus.

FIG. 4 is a fragmentary vertical sectional view through a furthermodified form of apparatus.

FIG. 5 is a fragmentary sectional View taken along the line 55 in FIG.4.

N'Ce

Referring to FIG. 1, a mold 10 is provided into which a gob of glass isdeposited by suitable means well known in the art and thereafter aplunger 11 is brought downwardly into contact with the glass and pressedto form the glass article.

As shown in FIG. 1, mold 10 comp-rises a base section 12 and aperipheral sec-tion 1 3 defining an internal molding surface 14 whichhas a configuration corresponding to the external configuration of theglass article which is to be formed. Peripheral section 13 includes aninwardly extending peripheral lip .15 which defines the upper end of theflange which is to be formed on the glass article.

As shown in FIG. 1, the plunger 1 1 also comprises an inner member 2 2and an outer member 21. The outer member is of substantially uniformthickness throughout and suflicient as to withstand the forces necessaryto press the article. The inner member 22 is made of a lighter gaugematerial such as sheet metal. The inner member 22 is spaced from theouter member 21 and includes a flange 22a which overlies flange portion27. A metal 243 is cast in situ inthe space between the inner and outermembers.

Outer member 21 includes a base portion 16 and a flange portion 17 andis mounted on a head 18 by bolts 19 threaded into flange portion 17 ofthe plunger 1:1. A gasket 20 is interposed between the flange 22a andhead 18. Head 18 is adapted to be moved upwardly and downwardly by asuitable mechanism (not shown), known in the art, such as a hydraulicram.

A distributor 25 is provided between the head 18 and plunger 11 andcomprises a circular plate 26 and a hub 27 at the center of the plate.Bolts extend through circumferentially spaced bosses (not shown) tosupport distributor 26 on the lower end of head 18. A lip 26a is formedon the periphery of plate 26 and extends upwardly into contact with agasket 20. Liquid coolant is forced under pressure throughcircumferentially spaced vertical openings 30 in head 18 into the space40 between plate 26 and the lower end of the head. A plurality ofnozzles is provided in the periphery of the distributor. Each nozzlecomprises a plug 31 threaded into an opening in the distributor. Eachplug is formed with a nozzle opening 32 which has its axis inclinedhorizontally to a radial plane intersecting the axis of the plunger 11.In this fashion, a plurality of streams or jets of liquid coolant aredirected at the area of juncture of .the periphery of base portion 22band flange 220 of inner memmer 22. An O-ning type gasket 33 is providedon the upper end of hub 27 to provide a seal and prevent the liquidcoolant from passing from the inlet directly to the outlet opening 34 inhead 18.

A disc 35 is provided below distributor 25 and includes a sleeve 36extending upwardly into hub 27. The upper end of sleeve 36 is spacedfrom the base of the opening of the hub into which it extends so thatdisc 35 has limited reciprocating movement relative to hub 27 and, inturn, distributor 25. Bolts (not shown) locked in position by lock nuts(not shown) are provided at circumferentially spaced points along theperiphery of disc 35 and extend through the disc into contact with theinner surface of base portion 16. By this arrangement, the lowermostposition of disc 35 is adjusted so that the disc is always out ofcontact with the inner surface of the member 22.

In operation, gobs of glass are periodically fed to mold 14 and plunger16 is moved downwardly into contact with each gob ,to form the glassarticle. During the operation of the forming equipment, liquid coolantis forced under pressure through openings 30 into the space between thelower end of head 18 and distributor 25. Coolant is then directed in aplurality of streams or jets at the area of juncture of the base portion16 and flange portion 17. Since the axes of the jets are at an angle toa radial line intersecting the axis of the plunger, a rotary motion isimparted to the coolant. The liquid coolant fills the space 40 betweenthe undersurface of plate 26 and the upper surface of disc 35 forcingdisc 35 downwardly and bringing the ends of bolts into contact with theinner surface 22b of inner member 22. The restricted flow through space39 between disc 35 and inner member 22 causes a small pressure dropwhich produces a differential pressure between the space 40 and thespace 41 insuring that the disc 35 is urged downwardly into properposition with respect to the surface.

The undersurface of disc 35 is so shaped relative to the surface ofinner member 22 of plunger 11 that the liquid, as it flows from theperiphery of the base portion to the center thereof, flows at a constantvelocity. In other words, the cross-sectional area of the space 41between the lower or undersurface of disc 35 and the inner surface ofbase portion 16 is such that it increases in size from the periphery tothe center so that a constant velocity of liquid will be permitted toflow. The liquid coolant is withdrawn through sleeve 36 and outlet 34.

The surface of the inner member 22 against which the coolant is directedis preferably roughened in order to obtain the best possible heattransfer. The roughening may be achieved by knurls or in any othersuitable manner such as ribs. The roughening should be sufiicient toinsure heat transfer but not so deep as to form stagnant pockets ofcoolant.

According to the invention, the thermal conductivity of the body of amold or plunger can be changed readily if the interior is such that itcan be readily placed in liquid form. Then the thermal conductivity canbe increased or decreased by inserting good or poor thermal conductingbodies in the liquid portion. The metal liquid Wetting the surface ofthe insert eliminates the need for welding because a wetted surface isthe equivalent of a metallurgical bond thermally. If the liquid portionis intentionally made so that it does not wet the insert, an interfacialheat barthermal insulation.

The idea and advantages of a liquid core mold or plunger are shown inFIG. 1. Assume first that the liquid metal wets the outer. and innermembers 21, 22 of plunger 11. Then the temperature drops will be in theouter and inner members 21, 22 and in the metal core 23. Since theliquid metal wets the members 21, 22 there is no interfacial heat lossthere.

Assuming the following conditions:

Heat flux density, 90,000 B.t.u./ft. /hr.

In the above computation the thermal conductivities of the metals wereassumed to be:

Stainless steel 180 B.t .u./ft. /hr./in./ F. Core metal 320 B.t.u./ft./hr./in./ F.

If it is assumed that the core metal does not wet the surfaces 21, 22and the interfacial impedance is 2000 B.t.u./ ft. F./hr. then thetemperature drop at each interface will be:

Since there are two interfaces the outer wall temperature will rise by 245=90 or 739+90=829 F. Thus, temperature control can be effected bychoosing or making the core metal wet or not wet the members 21, 22. Inaddition, non-wettable shims of the metal can be inserted into the coremetal to effect temperature rise on the outer surface. For example,assume that a two mil thick sheet is placed loosely over the innersurface of the outer member 21 such as 24 (FIG. 1). Each shim offers twosurfaces, thus two surfaces will be interposed. Then the additionaltemperature drop would be 2 4S=90. The glass contacting temperaturewould be 825+90=915 F.

Thus, wetting or non-wetting properties of surfaces become veryimportant factors and powerful aids in design of plungers and molds.

The above discussion shows that inserts can be added without additionalmachining in the cavity such as would be necessary in solid metalbodies. This is the greatest advantage of a metal core which can beliquified. Not only metals can be interposed into the thermal circuitbut also insulating bodies such as an asbestos barrier (FIG. 1).Inserting such barriers can prevent the loss of heat at the match line(the edge of the formed glass) where excessive heat losses and low heatinputs normally cause the outer surface of the plunger to run cold. Thebarrier 50 cuts the loss of heat to the water-cooled inner wall 22 to avery low value, and thus raises the temperature at the match line. Thus,interface and thermal barriers reduce the heat flow and raise thetemperature of the glass contacting surface.

Also, a good thermal conductor can be inserted to carry heat from pointsof heat concentration to points of heat deficiency. For example, at thearea of juncture of the base and flange portions of the plunger, thegeometry concentrates the heat causing the outer surface at the radiusto run hot. By placing a copper strap 51 (FIG. 1) which is a good heatconductor between the radius and match line, heat can be conducted rieris established which can be utilized as a form of from the high fluxdensity area to the low flux density area and thus raise the temperatureat the match line, and lower it at the radius.

The remaining excess heat flux from the radius can be carried into thecooling wall by another copper strap 52 as it extends .from the radiusto the inner watercooled wall 22. The amount of heat that both straps 51and 52 carry is a function of the temperature difference at their endsand the dimensions of the straps. Since the liquid metal wets both thecopper and stainless steel walls, welding or brazing the copper strapsto the walls is not necessary. It is only necessary that the copperstraps be held in position by any convenient means such as wedging,bracing bolts or rivets driving the casting of the core 23 into theplunger.

Another advantage of the liquefiable core center is that its thermalconductivity as a unit can be easily changed by changing the compositionof the core metal. For example, if a plunger operating satisfactorily atsix pressings per minute with a core of liquid is speeded up to operateat eight pressings per minute, the heat flux would increase so :muchthat the plunger surface would become too hot. By changing the coremetal from tin to cadmium, the average thermal conductivity of theplunger is increased so much that the surface temperature drops to thenormal satisfactory level. Thus, an easy change in thermal conductivityis made. without altering the design. If the plunger were made of solidmetal, the entire plunger would have to be discarded or receiveextensive machining.

Liquid metals may expand and contract a great deal with small changes intemperature. Thus, a practical production or mold may require expansionspace. This is provided in FIG. 1 by filling the space only to a littleabove the match line, leaving a gas space 28 above as an expansionchamber. This gas space can be filled with a reducing or neutral gas toprevent the liquefiable core metal from oxidizing if it is subject tooxidizing. Such a gas serves the added function of thermal insulatorbetween the plunger, the cooling water and the plunger head. By raisingor lowering the level of the core metal, the thermal conductivitycontrol can be varied. This concept can be extended to other parts ofthe plunger or mold. Hollow spaces can be provided which can be filledor emptied of metal as the operating surface temperature demands andthus achieve temperature control.

As shown in FIG. 4, these hollow spaces can be a thin flat tube 55extending circumferentially. They would have maximum conductivity whenfull and lesser conductivity achieved by varying the level of gas and,in turn, liquefiable metal in tube 35.

As shown in FIG. 3, the use of liquid metal as a mechanically flexibleheat transfer path permits the use of thin shell forming surfaces. Athin shell 40 formed by spinning, hydroforming or other low cost formingmethods can be slipped over a heavier base 41 and the two connectedthermally by a thin film 42 of liquefiable metal. In making the plungershown in FIG. 3, the liquid metal is first placed in the shell 40 andthen the base 41 is inserted causing the liquid met-a1 to rise and fillthe thin space between the -base 41 and shell 40. The liquefiable metal42 carries the heat from the thin shell 40 into the base metal 41 whereit is dissipated by air or water cooling. If the shell 40 is damaged orworn it can be slipped off the base 41 and replaced by another one.vThis form of construction utilizes low cost material and finishingoperations in replacing wearing surfaces of molds and plungers.Heretofore this has not been feasible because metallurgical bondsbetween the shell and base material could not be made Without voids andwere otherwise excessive in cost.

I claim:

1. A pressing member for pressing gobs of molten glass intopredetermined shapes comprising a body having a forming surfacecorresponding to a surface of the article which is to be formed,

said body comprising a first wall having said forming surface formedthereon and a second Wall spaced from the first wall and cooperatingtherewith to define a closed space,

at least one thermal modifying member in said space,

and a metal cast in situ in said space about said thermal modifyingmember and substantially filling said space,

said cast metal having a melting point which is less than the meltingpoint of said body and which is such that the major portion of the massof the cast metal is solid at the operating temperatures of the pressingmember and has a thermal conductivity such that upon operation of thepressing member to press gobs of molten glass, heat transfer occurs 5through the metal.

2. The combination set forth in claim 1 including an opening in saidbody to said space in said body whereby said cast metal can be meltedand removed for replacement with a metal having a different thermalconductivity.

3. The combination set forth in claim 1 wherein said thermal modifyingmember is thermally metallurgically bonded to said cast metal.

4. The combination set forth in claim 3 wherein said thermal modifyingmember has a greater thermal conductivity than the body and the castmetal.

5. The combination set forth in claim 1 wherein said thermal modifyingmember has a lesser thermal conductivity than the body and the castmetal.

6. The combination set forth in claim 1 wherein said thermal modifyingmember comprises a hollow tube in said closed space,

said tube having at least one opening therein whereby said metal cast insitu in said body enters and partially fills said body.

7. The combination set forth in claim 1 including a head,

means for supporting said pressing member on said head,

and means for directing a coolant onto the inner wall of said pressingmember,

and means for removing said coolant,

whereby liquid coolant is caused to move across the inner wall of thepressing member to cool the pressing member and as the pressing memberis operated to press successive gobs of molten glass, heat transferoccurs through the body and the metal therein to the inner wall of thepressing member which is contacted by the liquid coolant.

8. The combination set forth in claim 7 wherein said outer wall hassubstantially unifonm-thickness.

References Cited by the Examiner UNITED STATES PATENTS 780,863 1/1905Coleman 356 1,965,242 7/ 1934 Kelly 249-11 1 3,003,287 10/1961 Torok 65319 5 DONALL H. SYLVESTER, Primary Examiner,

A. D. KELLOGG, Assistant Examiner.

1. A PRESSING MEMBER FOR PRESSING GOBS OF MOLTEN GLASS INTOPREDETERMINED SHAPES COMPRISING A BODY HAVING A FORMING SURFACECORRESPONDING TO A SURFACE OF THE ARTICLE WHICH IS TO BE FORMED, SAIDBODY COMPRISING A FIRST WALL HAVING SAID FORMING SURFACE FORMED THEREONAND A SECOND WALL SPACED FROM THE FIRST WALL AND COOPERATING THEREWITHTO DEFINE A CLOSED SPACE, AT LEAST ONE THERMAL MODIFYING MEMBER IN SAIDSPACE, AND A METAL CAST IN SITU IN SAID SPACE ABOUT SAID THERMALMODIFYING MEMBER AND SUBSTANTIALLY FILLING SAID SPACE, SAID CAST METALHAVING A MELTING POINT WHICH IS LESS THAN THE MELTING POINT OF SAID BODYAND WHICH IS SUCH THAT THE MAJOR PORTION OF THE MASS OF THE CAST METALIS SOLID AT THE OPERATING TEMPERATURES OF THE PRESSING MEMBER AND HAS ATHERMAL CONDUCTIVITY SUCH THAT UPON OPERATION OF THE PRESSING MEMBER TOPRESS GOBS OF MOLTEN GLASS, HEAT TRANSFER OCCURS THROUGH THE METAL.